Conor McGregor was beaten on his UFC return as Khabib Nurmagomedov delivered a career-best display – but the Russian was seemingly the instigator of a post-fight melee.

McGregor was making his comeback to mixed martial arts after a near two-year hiatus but he submitted to his rival’s rear-naked choke midway through the fourth round at UFC 229 in Las Vegas.

Nurmagomedov therefore retained his lightweight title and then, immediately afterwards, threw his gumshield, mounted the cage and looked to attack to someone from McGregor’s team.

While that was happening, McGregor was set upon and attacked by two men who entered the cage as the bad blood that had been building up ahead of this fight came to a head.

UFC president Dana White later confirmed in a post-fight press conference that the Nevada State Athletic Commission had withheld Nurmagomedov’s payment pending an investigation into the post-fight melee.

However, McGregor’s payment was released.

Three members of Nurmagomedov’s team were arrested following the scenes at the end of the bout but were released soon afterwards when McGregor said he would not press charges, according to White.

The Irishman did not appear to be unduly hurt once officials had surrounded him and protected him from further damage but this is a devastating defeat against one of his most bitter foes.

Nurmagomedov, who was ahead on all three of the judges’ scorecards at the time of the stoppage, was not presented with his belt and neither were there any interviews, as is customary after a title fight.

The enmity between the pair escalated earlier this year when McGregor notoriously threw a dolly at the window of a bus containing several rival fighters, including Nurmagomedov, and the war of words had intensified ever since.

McGregor was bidding to retain the title he never lost in the cage, having been stripped of his featherweight and lightweight titles due to his inactivity from the octagon.

His last MMA fight came in a win over Eddie Alvarez in November 2016, when he became the first person to simultaneously hold UFC titles in two different categories.

In the interim period, he had a foray into boxing for a lucrative showdown with Floyd Mayweather and was said to have earned 100million US dollars from the bout.

His comeback and the level of opponent generated so much hype that the UFC billed the event as the biggest in the organisation’s history, with a new benchmark for pay-per-view buys forecast.

In a bout that pitted striker against wrestler, it was thought that Nurmagomedov’s best chance of maintaining his unbeaten record and his crown was to absorb some early blows before using his superior grappling technique to punish a tiring McGregor.

However, it was the Dagestan native who came out with intent, ignoring a cascade of jeers, as he has faced all week from a largely pro-McGregor crowd, many of whom made the trip over the Atlantic for this weekend.

Nurmagomedov took down the challenger in an opening round that will not live long in the memory, McGregor backed up against the cage and landing a few elbows while on the floor.

Nurmagomedov landed a couple of decent blows at the conclusion of the first five minutes, setting the scene for a memorable second round in which he floored McGregor with a haymaker before a ferocious ground and pound.

McGregor was forced to cover up but he withstood the barrage and had a customary smile on his face as he swaggered back to his stool at the end of the round.

He had a welt under his left eye but he perhaps shaded the next round, in which Nurmagomedov opted to stand and trade with McGregor, the two matching each other blow for blow.

A takedown in the fourth precipitated the beginning of the end for McGregor, who allowed his opponent to mount his back and lock in a hold that forced McGregor to submit for the fourth time in his career three minutes and four seconds into the round.

That was only the start of the drama, though, with chaos ensuing in the moments after the end of the fight.

McGregor left the T-Mobile Arena to a rapturous ovation while Nurmagomedov was predictably booed on his exit from the venue.